linux-kernel - Re: [PATCH v2 2/8] iio: at91-sama5d2_adc: pass ref to IIO device via param for int function

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Date:   Sat, 16 May 2020 18:15:22 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Alexandru Ardelean <alexandru.ardelean@...log.com>
Cc:     <linux-iio@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-kernel@...r.kernel.org>, <ludovic.desroches@...rochip.com>,
        <eugen.hristev@...rochip.com>, <nicolas.ferre@...rochip.com>,
        <alexandre.belloni@...tlin.com>, <alexandre.torgue@...com>,
        <mcoquelin.stm32@...il.com>, <ak@...klinger.de>
Subject: Re: [PATCH v2 2/8] iio: at91-sama5d2_adc: pass ref to IIO device
 via param for int function

On Thu, 14 May 2020 16:17:04 +0300
Alexandru Ardelean <alexandru.ardelean@...log.com> wrote:

> Since there will be some changes to how iio_priv_to_dev() is implemented,
> it could be that the helper becomes a bit slower, as it will be hidden away
> in the IIO core.
> 
> For this driver, the IIO device can be passed directly as a parameter to
> the at91_adc_no_pen_detect_interrupt() function, thus making it immune to
> the change of iio_priv_to_dev().
> The function gets called in an interrupt context.
> 
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>

Looks sensible to me.   We could get the state structure from the 
iio_dev inside that function, but then it would be different from the
pen version, so I think what you have here is probably best option.

Jonathan

> ---
>  drivers/iio/adc/at91-sama5d2_adc.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index 9abbbdcc7420..822b8782acba 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -1275,10 +1275,9 @@ static void at91_adc_pen_detect_interrupt(struct at91_adc_state *st)
>  	st->touch_st.touching = true;
>  }
>  
> -static void at91_adc_no_pen_detect_interrupt(struct at91_adc_state *st)
> +static void at91_adc_no_pen_detect_interrupt(struct iio_dev *indio_dev,
> +					     struct at91_adc_state *st)
>  {
> -	struct iio_dev *indio_dev = iio_priv_to_dev(st);
> -
>  	at91_adc_writel(st, AT91_SAMA5D2_TRGR,
>  			AT91_SAMA5D2_TRGR_TRGMOD_NO_TRIGGER);
>  	at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_NOPEN |
> @@ -1318,7 +1317,7 @@ static irqreturn_t at91_adc_interrupt(int irq, void *private)
>  		at91_adc_pen_detect_interrupt(st);
>  	} else if ((status & AT91_SAMA5D2_IER_NOPEN)) {
>  		/* nopen detected IRQ */
> -		at91_adc_no_pen_detect_interrupt(st);
> +		at91_adc_no_pen_detect_interrupt(indio, st);
>  	} else if ((status & AT91_SAMA5D2_ISR_PENS) &&
>  		   ((status & rdy_mask) == rdy_mask)) {
>  		/* periodic trigger IRQ - during pen sense */